Browning A Bolt, Sako A7, Steyr (fits long and short actions ): Base screws are 6-48 X 1/4? long. Ring screws are 6-40 X 5/8? long. Both use a 7/64 Allen wrench. Hole spacing dimensions on front mount and back mount are .86?. Both mounts are the same part. Standard rings are .63? wide and Tactical rings are .80? wide. Standard rings have 2 screws per ring and Tactical rings have 4 screws per ring. Height of mounts from top of receiver to centerline of scope tube is - low .94?, medium 1.06?, and High 1.19?. 2 Screws.